GB2088393A

GB2088393A - Anhydride-group- or carboxyl-group-containing graft copolymers of polysaccharide esters a process for their production and their use

Info

Publication number: GB2088393A
Application number: GB8136171A
Authority: GB
Original assignee: Bayer AG
Current assignee: Bayer AG
Priority date: 1980-12-03
Filing date: 1981-12-01
Publication date: 1982-06-09
Also published as: DE3045487C2; FR2495164A1; US4501871A; DE3045487A1; GB2088393B; JPS57119910A

Description

1

GB 2 088 393 A 1

SPECIFICATION

Anhydride-group- or carboxyl-group-containing graft copolymers of polysaccharide esters, a process for their production and their use

> 5 This invention relates to graft copolymers of vinyl esters and monomers containing anhydride " or carboxyl groups on polysaccharide esters, to their production by radical polymerisation in homogeneous solution and to their use for the , 10 production of films, foils or fibres.

Frequent attempts have been made to modify cellulose esters by grafting on side chains or vinyl compounds either with a view to making the cellulose esters more readily processible or to 15 providing them with better service properties.

For example, it is known from German Auslegeschrift No. 1,155,107 that vinyl acetate and other monomers, such as styrene or acrylonitrile, can be grafted onto cellulose 20 derivatives, such as cellulose ethers or cellulose esters, by ionising radiation.

It is of particular interest to produce products which show the favourable mechanical fibre-forming and film-forming properties of cellulose 25 esters, but which in addition contain reactive groups.

One problem which has not yet been satisfactorily solved in this respect, particularly in the case of cellulose acetates, is that their graft 30 products are neither homogeneous nor even compatible in themselves because it is only products of that type which could be expected to have good mechanical properties.

It has now been found that graft polymers of 35 cellulose esters and also graft polymers of other linear polysaccharides, such as graft polymers of amylose, can be obtained by radially polymerising vinyl esters, preferably vinyl acetate, and suitable derivatives of maleic acid and/or fumaric acid in 40 homogeneous solution in the presence of polysaccharide esters.

One particularly important factor in this respect is the ratio of the polysaccharide esters to the monomers to be grafted on and, in their case, the 45 ratio of the maleic acid and/or fumaric acid derivatives and the vinyl esters to one another. The ratio by weight of the polysaccharide fractions to the copolymers to be grafted on should amount to from 1:0.1 to 1:2 and preferably from 1:0.2 to 50 1:1.

1 The molar ratio of the maleic acid or fumaric acid derivatives to the vinyl ester should be from 1:0.5 to 1:3 and preferably from 1:1 and 1:2. » Maleic acid derivatives are preferred by virtue of 55 their better tendency towards copolymerisation.

Polysaccharide esters of aliphatic C,—C5-monocarboxylic acids are used as the graft substrate. The preferred polysaccharide esters are acetic esters of cellulose or amylose; in addition to 60 the acetic ester group, the polysaccharide ester may also contain propionic acid and butyric acid groups.

The processes for producing organic cellulose esters of this type have long been known and are

65 described, for example, in Ullmanns Encyklopadie dertechnischen Chemie (Verlag Urban & Schwarzenberg, Munich-Berlin, 1963), Vol. 5, pages 182 to 201. The cellulose acetates used are, above all, those in which 2 to 3 hydroxyl 70 groups of the basic molecules are esterified and which are normally known as cellulose diacetate and cellulose triacetate.

Cellulose acetobutyrates suitable for use in accordance with the invention contain 75 from 40 to 50% by weight of butyric acid groups and from 15 to 26% by weight of acetic acid groups,

whilst suitable cellulose acetopropionates contain 80 from 50 to 66% by weight of propionic acid groups and from 1 to 12% by weight of acetic acid groups.

Suitable vinyl esters are vinyl esters of C,—C1S-monocarboxylic acids, for example vinyl acetate, 85 vinyl propionate and vinyl benzoate, vinyl acetate being preferred.

Other unsaturated esters, for example the diesters of maleic acid and fumaric acid as well as acrylic acid or methacrylic acid esters, may also be 90 co-polymerised in small quantities.

Suitable maleic acid and fumaric acid derivatives are maleic acid anhydride and the semiesters of the two acids with aliphatic C,—C24-monoalcohols, preferably with Ci C10-95 monoalcohols which may optionally contain functional groups, for example with ethanol, n~ butanol, 3-hydroxy propionitrile and 2-ethyl hexyl alcohol.

Examples are maleic acid methyl semiester, 100 butyl semiester, ethyl semiester, cyclohexyl semiester, ethyl hexyl semiester, benzyl semiester or semiesters of abietic alcohol and corresponding semiesters of fumaric acid.

Accordingly, the present invention provides 105 anhydride-group- or carboxyl-group-containing graft copolymers of vinyl esters and other suitable monomers on polysaccharide esters, characterised in that they consist of

A) a polysaccharide ester, preferably of

110 cellulose or amylose, with at least one aliphatic

C1—C5-monocarboxylic acid as the graft substrate and

B) a grafted-on monomer mixture of a) a vinyl ester of a C1—C1g-monocarboxylic 115 acid, preferably vinyl acetate, and b) maleic acid anhydride and/or a semiester of maleic acid and/or fumaric acid with an aliphatic C,—C24-monoalcohol, preferably with a C,—C10-monoalcohol,

120 the ratio by weight of A) to B) being from 1:0.1 to 1:2 and preferably from 1:0.2 to 1:1.1, and the molar ratio of a) to b) being from 1:0.5 to 1:3 and preferably from 1:1 to 1:2.

The invention also provides a process for the 125 production of these graft copolymers which is characterised in that the monomer mixture is radically polymerised in homogeneous solution in the presence of the graft substrate in the ratio by weight and molar ratios indicated.

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GB 2 088 393 A 2

Suitable solvents are those which do not enter into any undesirable secondary reactions with maleic acid anhydride. It is preferred to use tert.-butanol, methylene chloride, glacial acetic acid or 5 mixtures thereof. However, it is also possible to use other solvents, such as acetic acid anhydride, acetone and dimethyl formamide, optionally in admixture with the solvents tert.-butanol and methylene chloride.

10 in the context of the invention, a homogeneous solution is also understood to be a dispersion of the polysaccharide esters and monomers in an aqueous medium where the solvent or the vinyl ester is not homogeneously miscible with water, 15 so that the polysaccharide ester is still present in at least swollen, albeit finely divided, form with the monomers or the solvent.

However, high grafting yields are obtained particularly readily in cases where methylene 20 chloride, tert.-butyl alcohol or glacial acetic acid is used as the solvent.

The initiators used are the usual radical-forming substances, for example organic peroxides, such as lauroyl peroxide and di-tert.-butyl peroxide, 25 peroxydicarbonates, such as diisopropyl peroxydicarbonate, tert.-butyl hydroperoxide and tert.-butyl perpivalate, or readily decomposable azo compounds, such as azodiisobutyronitrile. Polymerisation may, of course, also be initiated by 30 short-wave radiation. The initiators are preferably used in quantities of less than 1 % by weight,

based on the total quantity of graft base and monomers.

Polymerisation is generally carried out at 35 temperatures in the range of from 10 to 120°C and is adapted to the corresponding decomposition temperature of the radial former. Other temperature ranges may, of course, also be applied where redox initiators are used and where 40 polymerisation is initiated by ionising radiation. However, polymerisation is preferably initiated by radical-forming peroxides or azo compounds at temperatures in the range of from 20 to 100°C.

Polymerisation by the process according to the 45 invention gives very high grafting yields as reflected in the fact that the copolymers of the maleic acid derivatives and vinyl esters, which are insoluble in methylene chloride and which are precipitated as a deposit during polymerisation, 50 remain in homogeneous solution as grafted-on compounds where polymerisation is carried out in the presence of the polysaccharide esters. The high degrees of grafting are also reflected in the fact that the graft products as such are also 55 homogeneous substances, which may be verified very easily from their film properties because the graft products as such give glass-clear films, whereas corresponding mixtures of polysaccharide esters and the ungrafted 60 copolymers give clouded films, occasionally with pronounced island formation, which is attributable to the presence alongside one another of the two incompatible macromolecular substances.

The products according to the invention may 65 readily be processed from solution to form films.

foils and fibres characterised by good mechanical properties. For example, fibres of cellulose acetate graft copolymers are more hydrophilic, show greater affinity for basic dyes and a lesser tendency towards electrostatic charging.

The invention is illustrated by the following Examples.

EXAMPLES

I. In a 2-litre stirrer-equipped vessel, into which a gentle stream of nitrogen is continuously introduced (approximately 2 l/h), 160 parts by weight of cellulose 2-g- acetate and 21.3 parts by weight of maleic acid anhydride are dissolved, while stirring at 20°C, in a mixture of 640 parts by weight of methylene chloride and 160 parts by weight of tert.-butanol. A solution of 0.2 part by weight of dicyclohexyl peroxydicarbonate in 21 parts by weight of vinyl acetate is then added at 20°C. After stirring for another 10 minutes at 20°C, the internal temperature is increased to 40°C, followed by stirring for another 10 hours under a light nitrogen blanket.

After cooling to 20°C, the clear solution is precipitated by stirring into 3000 parts by weight of petroleum ether (Bp. 60—70°C), and the white product precipitated is washed with 1000 parts by weight of petroleum ether and then dried at 70°C.

After drying 192 parts by weight of graft copolymer are obtained. Completely transparent films are formed from a tetrahydrofuran solution. The intrinsic viscosity (as measured in acetone) amounts to 1.02.

II. The procedure is as described in Example I, except that polymerisation is carried out in the absence of a graft substrate (cellulose 1\ acetate) under otherwise the same conditions. The copolymer of vinyl acetate and maleic acid anhydride is precipitated. 32 parts by weight of the copolymer are obtained after filtration under suction and drying. This may be regarded as proof of the fact that the proportion of vinyl acetate and maleic acid anhydride polymerised in Example I was fully grafted because a clear solution was formed.

III. 100 parts by weight of cellulose 2\ acetate and 53.3 parts by weight of maleic acid anhydride were dissolved as in Example I in a mixture of 640 parts by weight of methylene chloride and 160 parts by weight of tert.-butanol. After the addition of a solution of 0.5 part by weight of dicyclohexyl peroxydicarbonate in 52 parts by weight of vinyl acetate, the reaction mixture was stirred for 10 minutes at 20°C and polymerised for 10 hours at 40°C. After precipitation with petroleum ether and drying, 184 parts by weight of graft copolymer having an intrinsic viscosity of 1.35 (as measured in acetone) were obtained.

IV. The procedure was as in Example III using as the graft substrate 100 parts by weight of a cellulose acetopropionate having a propionic acid content of 57.4% by weight, an acetic acid content of 5.7% and an OH-number of 56.3.

187 parts by weight of graft copolymer having an intrinsic viscosity of 1.43 (as measured in

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GB 2 088 393 A 3

acetone) were obtained.

V. 160 parts by weight of the cellulose acetobutyrate described in Example IV and 54 parts by weight of maleic acid-n-butyl semiester

* 5 were dissolved in 800 parts by weight of i. methylene chloride. After complete dissolution, a solution of 0.5 part by weight of dicyclohexyl peroxydicarbonate in 33 parts by weight of vinyl acetate was added at 20°C. The mixture was then 10 stirred first for 10 minutes at 20°C and then for 10 hours at 40°C.

After precipitation in 3000 parts by weight of petroleum ether followed by drying at 70°C, 221 parts by weight of graft copolymer were obtained. 15 The intrinsic viscosity (as measured in acetone) amounted to 1.19. Glass-clear films were formed by drying from tetrahydrofuran solution. After storage in water at 20°C for 48 hours, none of the films showed any visible changes nor any increase 20 in weight through the absorption of water.

VI. 160 parts by weight of cellulose triacetate and 54 parts by weight of maleic acid-n-butyl ester were dissolved as in Example V in a mixture of 900 parts by weight of methylene chloride and

25 50 parts by weight of tert.-butanol. The further procedure was then as in Example V. 205 parts by weight of graft copolymer were obtained after drying.

VII. A mixture of 55 parts by weight of the

30 semiester formed from maleic acid anhydride and 3-hydroxy propionitrile and 33 parts by weight of vinyl acetate was grafted onto 160 parts by weight of cellulose triacetate under otherwise the same reaction conditions as described in Example 35 VI. 239 parts by weight of graft copolymer were obtained.

Claims

CLAIMS 1. Anhydride-group- or carboxyl-group-containing graft copolymers of vinyi esters and 40 other suitable monomers on polysaccharide esters of A) a polysaccharide ester of an aliphatic C,—Cs-monocarboxylic acid as the graft substrate and 45 B) a grafted-on monomer mixture of a) a vinyl ester of a C,—C18-monocarboxylic acid and b) maleic acid anhydride and/or a semiester of maleic acid and/or fumaric acid with an aliphatic 50 c,—C24-monoalcohol, the ratio by weight of A) to B) being from 1:0.1 to

1:2 and the molar ratio of a) to b) being from 1:0.5 to 1:3.

2. Graft copolymers as claimed in Claim 1, 55 wherein the ratio by weight of the graft substrate

A) to the grafted-on monomer mixture B) is from 1:0.2 to 1:1.1.

3. Graft copolymers as claimed in Claim 1, wherein the molar ratio of the grafted-on

60 monomers a) to b) is from 1:1 to 1:2.

4. Graft copolymers as claimed in Claims 1 to 3, wherein the graft substrate consists of esters of cellulose or amylose with aliphatic C.,—-C5-monocarboxylic acids.

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5. Graft copolymers as claimed in Claim 4, wherein the graft substrate consists of cellulose acetate, cellulose acetopropionate or cellulose acetobutyrate.

6. Graft copolymers as claimed in Claims 1 to 70 3, wherein the grafted-on monomer mixture consists of a) vinyl acetate and b) maleic acid anhydride and/or a maleic acid semiester with an aliphatic C1—C10-monoalcohol.

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7. A process for producing the graft copolymers of Claim 1, wherein from 0.1 to 2 parts by weight of a monomer mixture of a) 1 mole of a vinyl ester of a C,—C13-monocarboxylic acid and 80 b) from 0.5 to 3 moles of maleic acid anhydride and/or semiesters of maleic acid and/or fumaric acid with aliphatic C,—C24-monoalcohols are radically polymerised in homogeneous solution in the presence of 1 part by weight of a 85 polysaccharide ester of aliphatic C,—C5-monocarboxylic acids.

8. A process as claimed in Claim 7, wherein the solvent used is tert.-butanol, methylene chloride, glacial acetic acid or mixtures thereof. 90

9. The use of the graft copolymers claimed in Claims 1 to 6 for the production of films, foils and fibres.

10. A graft copolymer as claimed in claim 1, substantially as hereinbefore described with

95 reference to any of the Examples.

11. A process as claimed in claim 7, substantially as hereinbefore described with reference to any of the Examples.

12. A graft copolymer prepared by a process as 00 claimed in any of claims 7, 8 and 11.

13. Films, foils or fibres comprising a graft copolymer as claimed in any of claims 1 to 6, 10 and 12.

Printed for Her Majesty's Stationery Office by the Courier Press. Leamington Spa, 1982. Published by the Patent Office, 25 Southampton Buildings, London. WC2A 1 AY, from which copies may be obtained.